Effect of coagulant protein from Parkinsonia aculeata seed and Citrus juice on bacteria isolated from Ruvu River in Tanzania

Abstract

A total of 126 bacterial strains were isolated from water samples collected from Ruvu River in Tanzania. Seventy strains were identified by morphological, biochemical and 16s rRNA gene sequence analysis. The strains were found to belong to Acinetobacter, Pseudomonas, Vibrio, Aeromonas or Bacillus spp. Coagulant protein was purified from Parkinsonia aculeata seed by ion exchange chromatography. Antibacterial effect of the purified P. aculeata coagulant protein (PAP) and Citrus fruit juice (CF) was tested on four bacterial strains that belonged to different genera. Bacterial cell flocculation analyses showed that, PAP and CF aggregate both Gram-positive and Gram-negative bacteria. Growth studies of bacterial strains incubated with PAP and CF revealed that, inhibitory dosages of PAP ranged from 0.38 mg/L to 0.88 mg/L and growth inhibition occurred within two to four hours. The PACE and PAP showed high coagulation activities that were similar to those observed for chemical coagulant (alum) with turbidity removal efficiencies ranging from 93 to 98%. A simplified method used for purification of proteins together with high antimicrobial and water coagulation activity make proteins suitable for supplementing chemical coagulants in drinking water treatment. Also, CF is suitable for post disinfection of water treated with proteins prior drinking in poor communities.